1. Field of the Invention
The present invention relates to improved methods and compositions for placing particulate materials in subterranean zones including, but not limited to, forming gravel packs in well bores and forming and placing particulate materials in fractures.
2. Description of the Prior Art
In the completion and stimulation of wells penetrating subterranean zones containing hydrocarbons, it is often necessary to place particulate materials in the subterranean zones. An example of a well completion operation involving the placement of particulate material is gravel packing. In gravel packing operations, a solid particulate material such as graded sand is placed in a subterranean hydrocarbon producing zone between the zone and the well bore. The particulate material functions as a filter to separate formation solids from produced fluids while permitting the produced fluids to flow into and through the well bore.
An example of a subterranean zone production stimulation treatment in which particulate material is placed in the subterranean zone is hydraulic fracturing. In hydraulic fracturing, a viscous treating fluid, referred to in the art as a fracturing fluid, is pumped through the well bore into a subterranean zone to be stimulated at a rate and pressure such that one or more fractures are formed and extended in the subterranean zone. The viscous fracturing fluid carries a particulate material, referred to in the art as proppant material, such as graded sand into the fractures. The proppant material is suspended in the viscous fracturing fluid so that the proppant material is deposited in the fractures when the viscous fracturing fluid is broken, i.e., the viscosity of the fracturing fluid is reduced, and the fracturing fluid is recovered. The proppant material functions to prevent the formed fractures from closing whereby conductive channels are formed in which formation fines are filtered out of produced hydrocarbons and through which the produced hydrocarbons flow to the well bore.
In gravel packing and fracturing procedures, the particulate materials utilized are carried to the subterranean zone in which the particulate materials are to be placed by viscous carrier fluids. These carrier fluids can be water or oil based fluids and generally include a variety of chemical additives such as polymers, cross-linkers, clay control additives, pH control additives, fluid loss additives, surfactants, stabilizers, viscosity breakers, friction reducers and the like. It has been well established that the chemical additives in the carrier fluid can and often do cause damage to the hydrocarbon permeability of subterranean zones in which they are introduced. In addition, the various chemical additives included in the carrier fluids can be hazardous to the health of personnel in contact with the additives.
Thus, there are needs for improved methods and compositions for placing particulate materials in subterranean zones which do not utilize carrier fluids or chemical additives and do not damage the permeability of subterranean zones in which the particulate materials are placed.